Pretty much what the title says, I have Deathgreeter, and it says "Whenever another creature is put into a graveyard from play. You may gain one life." So if I use Ostracize on someone and discard one of their creatures, will I gain a life?
Unfortunately no, from play means from the battlefield
403.5. (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=403.5.): Previously, the battlefield was called the "in-play zone." Cards that were printed with text that contains the phrases "in play," "from play," "into play," or the like are referring to the battlefield. Cards that were printed with that text have received errata in the Oracle card reference.
Good to know. Thanks for the quick reply man!